The reference of repository in npm page is wrong. Change the package.json to fix.

PR Checklist

Please check if your PR fulfills the following requirements:

• [x ] The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x ] Other... Please describe: Fix docs related to npm

What is the current behavior?

The reference of repository in npm is "github.com/nestjs/config" which is wrong.

Issue Number: N/A

What is the new behavior?

The reference may be fixed. I am not sure because I never publish any package to npm.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information